Engineering atomic wavepackets in very-high-n Rydberg atoms

Author

Zhao, Wei

Date

2007

Advisor

Dunning, F. B.

Degree

Doctor of Philosophy

Abstract

The remarkable level of control of atomic wavepackets that can be achieved using very-high-n Rydberg atoms (n &ge; 350) is demonstrated. This control is accomplished with carefully-tailored sequences of short unidirectional electric-field pulses, termed half-cycle pulses (HCPs), with duration Tp &Lt; Tn, where Tn is the classical orbital period. In this limit, each HCP simply delivers an impulsive momentum transfer or "kick" to the Rydberg electron. We show that strongly polarized very-high-n (n &sim; 600) potassium Rydberg atoms can be produced by manipulating lower- n (n &sim; 350) polarized atoms. This enables us to study the response of such quasi-one-dimensional (quasi-1D) very-high- n Rydberg atoms to a periodic train of HCPs at high scaled frequencies, nu 0 > 15. Pronounced non-monotonic structure in the survival probability is observed as N, the number of HCPs in the train, is increased. This behavior is very sensitive to the polarization of the Rydberg states. A different protocol that enables us to localize and to steer Rydberg wavepackets in phase space is explained using classical phase-space portraits and confirmed experimentally by navigating phase-space localized wavepackets to targeted positions. Very-high-n quasi-1D Rydberg atoms also provide a valuable laboratory for studying irreversible dephasing, i.e., decoherence. This is demonstrated by observing the evolution of a Stark wavepacket containing states of different n in an external electric field. Based on a quantum beat echo technique we report the first demonstration of the reversibility of the dephasing of an ensemble of electric dipoles which is monitored by a probe HCP. This technique allows the measurement of decoherence in the presence of strong dephasing, which can be very important for quantum information processing. All experimental results are explained with the aid of classical trajectory Monte-Carlo simulations (CTMC) and good agreement is seen.